Full interval timing on dispatch machine



Oct. 5, 1954 R. A. BURGY FULL INTERVAL TIMING ON DISPATCH MACHINE 3 Sheets-Sheet 1 Filed Feb. 5, 1955 LOBBY INVENTOR. RAYMOND A 5036) 5, 1954 R. A. BURGY 2,691,149

FULL INTERVAL TIMING ON DISPATCH MACHINE Filed Feb. 5, 1955 3 Sheets-Sheet 2 IN V EN TOR.

' R y/wa/vb A. BURKE) Oct. 5, 1954 R. A. BURGY FULL INTERVAL TIMING ON DISPATCH MACHINE 3 Sheets-Sheet 3 Filed Feb. 5, 1953 JNVENTOR. RAYU/VD 4. EURG Y Patented Oct. 5, 1954 FULL INTERVAL TIMING; QN DISPATCH MACHINE Raymond A. Burgy, Maumee, (lhio, assignor to lilaug ton. El a or any, Toledo. Qh a a corporation of hio Application February 5, 1953, Serial No. 335,277

(01. wile-e20) 11 Claims.

This invention relates to control systems for banks of passenger elevators and in particular to improvements in the signaling means for dispatching the cars at timed intervals from the terminal floors.

In order to secure th most efficient service from a bank of elevator cars serving a plurality of floors it is necessary that the cars be dispatched from the principal loading floor and the other terminal floor at regularly timed intervals. Automatic mechanism commonly referred to as dispatching machines are arranged to give timed signals for the departure of the cars. These systems are satisfactory as long as the cars leave promptly upon receiving a signal and provided no cars leave prior to the receipt of a signal. These dispatching machines are used in conjunction with car selecting means that are arranged to route the g" signal to that car which was first to arrive at the terminal floor. In the event there are three or more cars at the terminal floor the car selecting mechanism, as one car leaves, ignores the order of arrival and selects the next car to go from the cars then at the floor according to a predetermined order which is preferably the order of the cars starting from the lobby door and proceeding along the bank of elevators.

During heavy incoming traffic conditions it often happens that a car may become loaded at the lobby floor and leave prior to the receipt of its go signal. With the usual type of dispatch mechanism the next car to leave receives the go signal that should have sent the preceding car on its way and as a result gets a go signal before it has had time to load. Should the second car depart as soon as it receives the signal it upsets the dispatching of the cars and results in light loading for some cars even during a rush hour. If the cars wait for a full load each time the dispatching schedule is thrown completely out of step.

The principal object of this invention is to provide a dispatching mechanism that is automatically accelerated or retarded according to the premature departure or late departure of the cars in relation. to the dispatching signals.

Another object of the invention is to provide a dispatching mechanism the timing portion of which is automatically reset upon the premature departure of a car to keep the dispatching mechanism in step with traffic demands.

A still further object of the invention is to provide an elevator dispatching mechanism in which a loaded car may depart as soon as loaded without materially varying the dispatching time interval. for the next car to leave.

A still further object of the invention is to provide a second drive mechanism for the dispatching machine which second drive mechanism is arranges to rapidly advance the dispatching mechanism past the next signaling position upon the Z departure of a car that leaves without having received a so signal.

Another object of the invention is to provide a dispatching machine in which the timing drive is connected to the dispatching mechanism by means of a clutch and second drive is arranged to drive the dispatching mechanism at a speed which is greater than the speed of the timing drive and in which controls actuated by the dis: patching machine control the high speed drive.

More specific objects and advantages are apparent from the following description of a preferred form of the invention.

According to the invention a second motor or other drive mechanism is connected to the dis? patching machine and electrical circuits including contacts operated by the dispatching machine are arranged to energize the second motor in the event an elevator car departs from a ter= minal floor prior to the registration of a dispatch signal. The contacts opera-ted by the dispatch mechanism and included in the control circuit for the motor are arranged to desenergize the motor as soon as the dispatching mechanism has been reset to a position slightly beyond the sig nal generating position.

A preferred embodiment of the invention is illustrated in the accompanying drawings.

In the drawings:

Figure I is a schematic illustration of a bank of elevators to be operated according to the invention.

Figure II is a schematic view of a portion of a floor selecting machine such as is used with each elevator.

Figure III is a schematic wiring diagram of the controls for operating the improved dispatching mechanism.

Figure IV is a timing diagram for the cam operated switches of the dispatching mechanism.

Figure V is a schematic diagram of the drive for the dispatching mechanism.

Figure VI is a section through a clutch included in the drive mechanism illustrated in Figure V.

These specific figures and the accompanying description are intended merely to illustrate the invention but not to impose limitations on its scope.

The dispatching system constructed according to the invention may be employed in elevator systems having two or more cars, v Figure 1 illustrates schematically four of a plurality of cars which may be included in an elevator installation. Each individual elevator comprises a car I supported by a cable 2 that directed over a drive pulley 3 and connected to a counterweight 4. The drive pu ley i m unted 9 a shaft 5 or n el drive motor 6. The shaft 5 is also extended into .floor selecting I, there be ng o e su machineior each el vator heme de eva tor .o the banks in luding the d ive motor 5 J and floor selecting machines 1 are identical with each other and the various elevators of the bank are distinguished by using a suffix b when referring to the second elevator, a suffix when referring to the third, and a suflix d when referring to the fourth.

When two or four or any other even number of elevators are operating they are dispatched on an even schedule, i. e. dispatching signals are simultaneously given to cars waiting at the lobby and top terminal floor. If only two cars are operating this even dispatching system keeps the cars evenly spaced with one car going up as the other comes down. If four or a larger even number of cars are operating dispatching signals are still simultaneously given at the lobby and top floor but there may be cars in transit between the floors at the same time cars are awaiting signals at the terminal floors.

If an odd number of cars are operating the dispatching signals at the lobby floor are still given at the uniform time intervals as with even operation but the dispatching signals for the upper or top floor are each given one-half interval later than they would be if an even number of cars were operating. This provides the most satisfactory sequence of dispatching and keeps the cars well distributed whether an even or odd number is operating.

Referring to Figure II each of the floor selecting machines 1 includes along with other parts, not shown, a traveling carriage or bar 8 that is supported by a pair of drive chains 9 and Ill that are driven by a lower shaft H. The shaft II is driven by a reversible constant speed motor, not shown in the drawings, and is also connected through a differential gear mechanism to the elevator drive shaft 5. The differential gear mechanism drives a rheostat that controls the elevator drive motor 6. The floor selecting machine I includes a number of contact points l2 that are arranged in horizontal rows corresponding to the floors to be served by the elevator and in vertical rows or lanes there being one lane for each control function that is required in the operation of the elevator. Thus there is one vertical row or lane of contacts to operate the car position lights, one lane for the up stopping signals, one lane for the down stopping signals, and so forth for the other control functions. The carriage 8 has brushes I3 one for each lane of contacts. A top floor contact I4 and a lobby floor contact l5 are included in the car selection circuit of the dispatching mechanism and are employed to signal the arrival of a car at the corresponding terminal floor and the fact that the car is at that floor. Another set of contacts I6 and I! are arranged in the same lane as the terminal floor contacts M and I5 and are closely adjacent thereto. These contacts [6 and I! are used to signal the departure of a car from a terminal floor. The circuits to the contacts l6 and I1 are taken through the direction relays of the elevator so that no signal is given through the contacts 16 when the elevator is moving up or through the contacts I! when the elevator is moving down, i. 6. when the elevator is approaching a terminal floor. The circuits through the direction relays are completed so that the departure signal is given through the contact I! as the car moves up and a similar signal is given through the contact l6 when the car moves down.

Referring now to the schematic wiring diagram (Figure III) of the control system for the dispatching machine, a go signal is given at the wise a dispatching signal is given at the upper terminal floor whenever a second latch relay i9 is in its latched position. A latching coil 20 of the lobby floor dispatching relay I8 is energized by current flowing from a lead Ll through a lead 2i, the coil 28, a lead 22, contacts 23 of a time delay up-reset relay 24, a lead 25, cam operated contact 26, and lead 2! connected to a return line L2. The contacts 26 are periodically closed by a cam 28 mounted on a dispatching machine cam shaft 29. The camshaft 29 is driven by a timing motor 30 energized from the line Ll through a lead 31, normally closed contacts 32 of a timing motor control relay 33 and a lead 34 connected to the motor 30. A return line 35 connects the motor 30 to the return lead L2. In this arrangement the timing motor 30 runs at substantially constant speed as long as the motor control relay 33 is de-energized.

The second latch relay it which when energized transmits a dispatch or go signal to cars at the upper terminal floor is energized or drawn into its latched position whenever a circuit is completed from the line L! through leads 3G. latch or closing coil 3! of the relay ill, a lead 38, normally closed contacts 39 of a time delay down reset relay I), a lead ii and then through normally closed contacts of an odd-even relay 43 and cam operated contacts M or through normally open contacts 453' of the odd-even relay 43 and dispatcher contacts 45 to the return lead L2. The odd-even relay 43 is energized from the line L! through a lead All, control 5-3, lead it, energizing coil and lead 5! connected to the return line L2. The control 2-8 is arranged so as to complete the circuit whenever an odd number of elevators are operating and to open the circuit Whenever an even number are in operation. As far as the control 48 is concerned an elevator is in operation if its motor generator set is running and it is therefore in condition to make a trip.

A cam 52 on the cam shaft 29 which on rates the contacts a l is phased to close the contacts 44 simultaneously with the closing of the contacts 26. Therefore if the odd-even relay is deenergized, indicating an even number or elevators in operation, the dispatching relays l3 and i ii are energized simultaneously. The contacts 45 of the dispatching machine are operated by a cam 53 that is arrange-cl to close the contacts li onehalf interval after the operation of the contacts 4 1. Thus when the odd-even relay 23 is energized to close its contacts t5 and open the contacts 42 the down dispatching relay l9 energized one-half interval after the up dis-pater ing relay i8 is energized.

Once the dispatching relays H3 or 8 have been energized and latched they remain in that condition until the corresponding relay release coil 56 or is energized. The release coil 54- for the up dispatch relay (8 is energized by the car departure signal from the lobby floor. The circult for this coil may be traced from the lead Ll through one or another of leads Eta to corresponding to the various elevators. brushes 57a to Elsi, the brush El being that one of brushes i3 carried on the carriage 8 which cooperates with the contacts iii to ll inclusive. As the carriage 8 leaves its position corresponding to the lobby floor a circuit is momentarily completed from the lead Ll through the lead 56, brush 5?, contacts ll, direction relay contacts leads and thus stops the timing motor 36.

59 and till to the dispatch relay release coil 54 and from the coil through a lead 6! to the return lead L2. Likewise when the carriage ll moves downwardly from its position corresponding to the upper terminal floor a circuit is momentarily completed from the line L! through the lead 55, brush 5?, contact point 66, contacts 62 of a down direction relay and leads 63 to the relay release coil 55 and then through the lead ill to the return line L2. Through these circuits dispatching signals that are set up by the dispatching relays l8 and is are automatically canceled as soon a car leaves the corresponding terminal floor.

In the event that a car does not respond to its dispatching signal within a reasonable time, which is slightly less than half of one full interval, the timing motor relay 33 is energized as the cam shaft 29 turns its cams t4 and 65 to close contacts 66 and ill respectively. The contacts El are arranged to close slightly less than one half of a complete interval after the closing of the contacts 26. Likewise the contacts 65 are arranged to close slightly less than one half of a time interval after the closing of the contacts 48. If the contacts 6? close before a car has left the lower terminal floor in response to a dispatch signal from the relay 58 the closing of the contacts 67 completes a circuit from the line Ll through lead $8, operating coil 69 of the timing motor relay 33, now closed contacts Hi of the up dispatch relay l8, lead H, and the now closed cam operated contacts El. Energization of the timing motor relay coil 6% opens its contacts 32 At the same time if an even number of cars are operating and simultaneous dispatch signals are being given, the failure of a car to leave the upper terminal floor in response to a dispatch signal from the dispatch relay [9 allows the cam operated contacts El to energize the timing motor relay 33 through contacts 12 of the relay it and now closed contacts 73 of the odd-even relay 43. Should an odd number of cars be operating and the odd-even relay 53 be energized to close its contacts M the timing motor relay 33 is energized in the event that the dispatching relay is is not released prior to the closing of the contacts 66 which occurs slightly less than half of a time interval after the closing of the contacts 36 which closed the dispatch relay it. Thus if a car in operation fails to respond to its dispatch signal the dispatching machine runs nearly a half time interval and then stops until the car does respond or another car leaves from the same terminal.

It is also desirable in the event that a car leaves a terminal floor prior to its dispatcher scheduled departure time that the dispatching machine be automatically reset to a correspond ing position. This advance or retardation, preferably an advance, is provided by a reset motor l5, shown at the upper portion of Figure III, which is mechanically connected to drive the cam shaft 29 at a relatively high rate of speed. The motor 15 connected to an alternating current power lead L3 is energized through a lead 16, and one or the other of two circuits, the first including a lead l7, normally open contacts 18 of the up direction reset relay 2A, a lead 19, and

normally closed cam operated contacts 89 connected to a return line L4. The second circuit includes normally open contacts SI of the down reset relay 40, normally closed contacts 82 of the odd-even relay 43, and the contacts 80 connected to the return line L4. If the odd-even relay 43 is energized the circuit from the contacts 8'! is taken through odd-even rela contacts 83, lead 84 and normally closed cam operated contacts 85. A cam 86 mounted on the cam shaft are arranged to momentarily open the contacts 89 approximately of a time interval after the closing of the contacts 26. Likewise, another cam G! is arranged to open the contacts approximately X20 of an interval after the closing of the contacts 46.

The reset driving motor l5 is preferably an alternating current motor having two fields 88 and 89 one of which is connected directly to the lead it and the other of which is connected through a condenser 99 and resistor 9| to the lead 16. The reset motor 15 is thus operated whenever either of the reset timing relays 24 or y 46 are operated.

The reset relay 24 is inergized from the line Ll through normally closed contacts 92 of the timing motor relay 33, normally closed contacts 93 of an up dispatch timing relay 94, an operating coil 95 of the reset control relay 24 and contacts 96 of an up departure signal relay 97. The departure signal relay 9'! is momentarily energized as the carriage 8 starts up from its lower position by current flowing through the brush 5'! and contact ll, through lead 59, and a lead 98 connected to an operating coil 99 of the departure signal relay 9'1. The dispatch timing relay 94 is energized to interrupt the circuit for the reset relay whenever the dispatch relay I3 is latched and contacts 100 are closed to complete a circuit through an operating coil [SI of the dispatch timing relay 94.

Likewise, the down reset relay 6c is energized by circuits including the normally closed contacts 92 of the timing motor relay, contacts I02 of a down dispatch timing relay I03, operating coil I04 of the down reset relay All and normally open contacts I05 of a down departure relay I06. The down departure relay lilt has an operating coil lfll that is energized momentarily as the brush 5! of the carriage 8 slides over the upper departure signal contact 16. The down dispatch timing relay [03 has its operating coil HEB energized through normally open contacts I09 of the down dispatch relay l9.

The up dispatch timing relay B l, the down dispatch timing relay I03, the up reset relay 24 and the down reset relay 4!} are all of the quick pickup, slow-release type so that the closure of the normally closed contacts is delayed an appreciable time after the corresponding operating coil is de-energized. Under normal operating conditions in which a car does not leave before it receives its dispatch signal the energization and the latching of the dispatch relays l8 and i9 energizes the timing relays 94 and H93 so that they open their contacts 93 and W2 respectively thus interrupting the circuits to the operating coils 95 and Hi l of the reset relays 24 and til so that these relays cannot respond when the oleparture signaling relays 9t and I06 are momentarily operated as a car leaves a terminal floor. In the event that a car leaves a terminal floor before a dispatch signal has been given the corresponding contacts 93 or m2 will be closed while the departure signal relay operates, thus momen' tarily energizing the corresponding one of the reset relays 24 or 40. The operated one of these relays thereupon closes its contacts T8 or 8! to energize the reset motor 15 which turns the dispatch cam shaft 29 until the contacts 8.0 or 85 open, The slow dr p out of these relays allows the cam shaft to be reset before the relay releases. This advances the cam shaft 29 until it is in substantially the same position with respect to the prematurely departing car that it would have occupied had the car waited for its dispatch signal.

Attention is called to the fact that contacts 23 and 35] are included in the energizing circuits of the dispatch relays I3 and I9 so that one or the other of these dispatch relays is energized during the resetting operation. Thus if a car leaves the lower terminal floor before the up dispatch I8 is energized the relay 24 is operated to advance the cam shaft but the contacts 23 are also open so that the subsequent closure of the cam operated contacts 26 does not energize the up dispatch relay I8. However, the contacts 39 of the down reset All are closed during this time so that the down dispatch relay is energized during the resetting process. Therefore, if a car leaves the lower terminal floor prematurely the dispatching machine immediately resets itself by advancing a corresponding amount and in the process gives a dispatch signal to a car at the upper terminal floor. The net effect is an advance of the entire dispatching schedule to correspond to the early departure of the car.

'18 slow release of the dispatch timing relays 9d and H33 prevents operation of the reset relays 25 or 59 when a car starts in response to a dispatch signal. It should be noted that the dispatch relays I8 and I9 are unlatched at the same time that the departure signaling relays 9! and 56 are energized. However, the slow release of relays and I83 allows the departure signal 1 relays to open their contacts before the dispatch timing relays 94 and H33 close their contacts 83 and I52. If it were not for this requirement of a time dela the contacts 93 and IE2 could be included directly on the dispatch relays I8 and I9.

The time relation of the cams and hence of the operations controlled by the cam shaft 29 is illustrated in Figure IV. As shown therein the order of operation of the contacts starting from the top of the diagram is first the momentary closing of the contacts 66 approximately Ill degrees after the start of the cycle. Next comes the momentary closing of contacts 26- approximately 90 degrees after th start of the cycle. Then the contacts 88 open momentarily about 20 degrees after the closure of the contacts 26. In the event that a car does not leave in response to a signal the dispatching mechanism is stopped a little less than a half interval later when the contacts close to energize the timing motor relay 33.

Under odd scheduling operation the next operation is the closure of the contacts 48 at threefourths of a time interval after the starting point or a half interval after the closing of the contacts 2t. The momentary closing of the contacts 46 energizes the down dispatching relay IS. The final cam operation is the opening of the contacts 85 about degrees later. The opening of the contacts 85 stops the reset motor I5 in the event that resetting was required following an early departure of a car from the upper terminal floor.

The provision of the reset motor I5 and the resetting control relays 24 and thus make it possible and practical to allow the elevators to leave the terminal floors as soon as they are loaded without waitin for dispatch signals and without upsetting the balancing of the dispatching system. Thus, maximum use may be made of the available equipment and still provide regular timing intervals for loading during ordinary 8 trafiic conditions when a full load is not reached during a single interval.

Figures V and VI illustrate the requirements of the mechanical system for the improved dispatching mechanism. As seen in Figure V the timing motor 38 drives through a gear reduction unit I I53 to an output shaft I I I on which is loosely journaled an output gear H2. The gear H2 is part of a friction clutch assembly that includes a fixed pressure plate H3 and a second friction plate I I that is keyed to the shaft III. A helical compression spring II5 sleeved over the shaft I II and bearing against the keyed pressure plate I Iii maintains pressure on the clutch to drive the gear I I2.

The gear II 2 meshes with a larger gear H6 mounted on the cam shaft 29. The reset motor I5 has a gear I I! mounted on its armature shaft and meshing with the cam shaft gear H6. The force of the clutch spring H5 and the torque of the motor 75.3 are adjusted so that the motor I5 can slip the clutch during resetting operations but the friction of the clutch is sufficient to drive the motor I5 when it is de-energized.

The friction clutch is selected as the simplest arrangement for coupling the output shaft I I I of the speed reducer to the gear H2. If the device always operates in the same direction any of the various types of overrunnin clutches may be used in place of the friction clutch without varying the results obtained except for reducing the torque requirements of the motor I5.

Various modifications of the circuit and structure may be made Without losing the advantages of resetting a dispatching mechanism to correspond to early departure of an elevator car and the description of the preferred embodiment is to be considered as describing but not limiting the scope of the invention.

Having described the invention, I claim:

1. In a dispatching system for a group of elevator cars, in combination, contactor mechanism for generatin dispatching signals, a motor for driving said mechanism at a first speed, means for transmitting the signals to an elevator car next to leave, a terminal floor car-departure signaling means, an advancing motor operatively connected to the timer to drive the contact mechanism at a second speed greater than the first, controls for the advancin motor, a contact controlled by the contactor mechanism that opens when a dispatch signal is given, a contact that is closed by said car departure signaling means, a circuit including said contacts arranged in series adapted to energize said advancing motor controls, and a contact in said timer that opens upon completion of a dispatching signal, said contact being operatively connected to tie-energize the advancing motor control.

In a dispatching system for a group of elevator cars, in combination, a motor driven timer having a cam shaft and a plurality of contacts operated by the cams for generating timed dispatching signals, zneans for transmitting the signals to an elevator next to leave, car departure signaling means including a contact that momentarily closes as the car leaves, a contact in said timer that opens in timed sequence after the production of a dispatching signal, a second motor for driving the timer at an accelerated speed, control means for the second motor, a circuit including the car departure operated contact and a dispatcher controlled contact that opens as a dispatch signal is transmitted for energizing the second motor control means if a car leaves before the arrival of a dispatch signal, and a circuit including said timer contact for de-energizing the second motor control circuit.

3. In a dispatching system for a group of elevator cars, in combination, dispatching mechanism controlling a plurality of contacts including a first contact that is closed during a timing interval and that opens simultaneously with the production of a dispatch signal, and a second contact that opens subsequently to the completion of a dispatch signal, means for transmitting dispatch signals to an elevator car that is next to leave a terminal floor, means for signaling the departure of a car from the terminal floor, a circuit including in series said first contact and a contact closed by the car-departure signaling means, means energized by said circuit for accelerating the dispatching mechanism, and a circuit including said second contact operatively connected to de-energize said accelerating means, whereby said dispatching mechanism is advanced whenever a car to be dispatched leaves before the arrival of the dispatching signal.

4. In a dispatching system for a group of elevator cars, in combination, a dispatching mechanism for generating timed dispatching signals, a first contact that is operated by the dispatching mechanism and that opens as a dispatch signal is produced, a second contact operated by the dispatching mechanism and arranged to open subsequent to the production of a dispatch signal, means for accelerating the operation of the dispatching mechanism, a third contact that is momentarily closed as a car leaves a terminal floor, a circuit including the first and third contacts arranged to energize the accelerating means and a circuit including the second contact for de-energizing the accelerating means.

5. In a dispatching system for a group of elevator cars, in combination, a cam shaft carrying a plurality of cams, contacts operated by said cams, means for driving the cam shaft at a slow speed, a dispatching circuit connected through at least one of the cam operated contacts, a car-departure signaling circuit, means for driving the cam shaft at an accelerated speed, means for energizing said accelerated speed driving means comprising a circuit completed through a contact controlled by the cam operated contacts and a contact controlled by the departure signaling circuit, and means for de-energizing the accelerated driving means when said cam shaft reaches a pre-determined position.

6. In a dispatching system for a group of elevator cars, in combination, a cam shaft carrying a plurality of cams, contacts operated by said cams for generating dispatching signals, means for driving the shaft at a first speed, means for driving the shaft at an accelerated speed, means responsive to the position of said shaft for stopping the accelerated driving means at a predetermined position of the shaft, means for signaling the departure of a car, and means under the joint control of said cam operated contacts and the departure signaling means for starting said accelerated driving means when a car departs from a terminal floor prior to receipt of its dispatching signal.

7. In a dispatching system for a group of elevator cars, in combination, a timing mechanism having contacts adapted to generate dispatching signals, electrically controlled means for accelerating the operation of the timer, a circuit including a timer contact that opens subsequently to the transmission of a dispatching signal, said circuit being connected to de-energize said timer accelerating means, means for signaling the departure of a car, and means in-' cluding contacts controlled by the timing mechanism and the departure signaling means for energizing the accelerating means in the event a car leaves before the arrival of its dispatching signal.

8. In a dispatching system for a group of elevator cars, in combination, a motor driven shaft adapted to operate contacts in dispatching circuits at fixed positions of the shaft, means for accelerating said shaft, a set of contacts that open immediately following the rotation of said shaft past its dispatching position, circuit means including said set of contacts for ole-energizing the accelerating means immediately after the shaft passes its dispatching position, means for signaling the departure of a car, and circuit means including a contact operated by the dispatching circuits and the departure signaling means for energizing the accelerating means upon advance departure of a car.

9. In a dispatching system for a group of elevator cars, in combination, a shaft having cams adapted to operate switches in car dispatching circuits, a slow speed motor drive, a clutch operatively connecting the slow speed drive to the cam shaft, high speed drive means operatively connected to the cam shaft and adapted to drive the shaft at a speed greater than that provided by the slow speed drive and clutch, means for signaling the departure of a car means including car dispatching circuits and said signaling means for energizing the high speed drive, and means including a contact opened by said shaft at a pre-determined position for de-energizing the high speed drive.

10. In a dispatching system for a group of elevator cars, in combination, a timing mechanism having a cam shaft and cam operated contacts adapted to generate dispatching signals, said cam shaft having a reference position that is reached shortly after the generation of a dispatch signal, means for driving the cam shaft at timing speed, means for signaling the departure of an elevator from a terminal floor, and means jointly controlled by said dispatching signal means and said car departure signaling means for immediately setting said cam shaft to said reference position upon the receipt of a car departure signal prior to a dispatch signal.

11. In a dispatching system for a group of elevator cars, in combination, a timing mechanism having a cam shaft and cam operated contacts adapted to generate dispatching signals, a cam contact that is opened as the cam shaft passes a reference position immediately after the completion of a dispatching signal, means for turning said cam shaft at timing speed, means for signaling the departure of elevator cars from the terminal floors, and means for resetting said cam shaft to its reference position,said resetting means being energized by the receipt of a car departure signal prior to the generation of a dispatch signal and being de-energized by the opening of said cam contact as said shaft reaches its reference position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,909,049 Ellis May 16, 1933 1,948,748 Ellis Feb. 27, 1934 2,291,271 Williams July 28, 1942 

